This may seem small, but I don’t think it is. I know it will seem old-fashioned. It has to do with a great nation’s sense of its own stature on the world stage.

In the days after the apparent murder of the Saudi activist and writer Jamal Khashoggi, President Trump was repeatedly pressed about the potential U.S. response if it turned out, as seemed likely, Crown Prince Mohammed bin Salman had ordered the killing. Mr. Trump made it clear his first consideration was what he thought of as a practical one: He didn’t want to cancel lucrative arms deals with the Saudi government. “I don’t like the concept of stopping an investment of $110 billion into the United States,” he said. That number was inflated, but Saudi Arabia is the largest purchaser of U.S. weapons.

Mr. Trump told Lesley Stahl of “60 Minutes”: “I don’t want to hurt jobs. I don’t want to lose an order like that.” Later in the week he told reporters that Saudi Arabia is a “tremendous purchaser” of U.S. military equipment, and this must be factored in.

It was startling. We talk like this now? In public? I guess it’s supposed to look tough and bottom-line. But we declare now that U.S. foreign policy is quite so transactional?

President Trump and Crown Prince Mohammed bin Salman

We used to be ashamed, or at least embarrassed, to be seen as arms merchant to the world. It didn’t quite sit with our vision of ourselves. And American presidents, as representatives of a nation with a certain moral stature, didn’t use to declare that our world stands are heavily influenced by arms contracts.

We used to play it a little more high-minded. Because we didn’t want the world to see us as crude and mercenary. And even if our discretion was hypocritical, it was at least the tribute vice pays to virtue.

All this made me think of George Bernard Shaw’s “Major Barbara,” in which Andrew Undershaft, the contentedly amoral manufacturer of cannons, guns, torpedoes and aerial gunships, shares the “true faith” of the munitions maker: “To give arms to all men who offer an honest price for them, without respect of persons or principles.”

But he was not precisely the good guy of the drama. America has always thought it is, and its reality should never veer far from its sense of itself. Trouble always happens when it does.

There are reasons to make arms, and not only economic but technological and strategic reasons to want America, not China or Russia, making them. But the fact that the defense industry is so big, and that people-blower-uppers is one of our major exports, ought to bring a certain and regular human discomfort and self-reflection. Arms industry profits shouldn’t be—and should never be announced as—a primary consideration in our foreign-policy decisions. How does that make us look better to any other people? Or even to ourselves?

The context for all this is the election, which is possibly why the president reverted so quickly and crudely to jobs.

The common wisdom a year ago leaned on history: The president’s party loses in an off-year, the only question is how much. It then became “Trump is so divisive and his approval numbers so underwater, a blue wave is coming.” Recently it was “Not so fast—the Democrats are confused as to their meaning and method. They could blow this thing.”

Then Brett Kavanaugh. After the onslaught he faced, Republicans were energized, especially in red-leaning states, where a rough wisdom took hold: Even a guy you don’t especially like can get railroaded. And this guy was being railroaded. It gave a boost to Republicans in U.S. Senate races that may or may not diminish.

Larry Sabato of the University of Virginia Center for Politics sees the Democrats close to winning the House but not there yet. They need to gain 23 seats. At the moment Mr. Sabato says they look to be in the mid to high teens.

There are 2½ weeks to go, which is plenty of time for the gates of hell to burst open. Both parties are focused and on fire. Each is being reminded of at least one big issue.

For Democrats it is a part of ObamaCare that people like, mandated coverage for pre-existing conditions. A Wall Street Journal analysis noted about 130 million nonelderly people in the U.S. suffer from an existing medical condition, and included a poll by the Kaiser Family Foundation that found 75% of voters consider it “very important” that the provision guaranteeing their coverage remain. For Republicans a longtime issue may well reassert itself, illegal immigration, and what Reuters calls “a caravan of several thousand” currently coming north from Central America.

Democrats also have the unpopularity of the president working in their favor, and Republicans have warnings of the return of a liberal House led by Nancy Pelosi. Republicans have, too, the rising spleen of the left, which is scarifying to the peaceful and will likely bring a backlash.

Both parties are spending record amounts, with Democrats running for the House and Senate raising over $1 billion through September, and the Republicans around $700 million, according to the Washington Post.

But in the end it’s about Mr. Trump, isn’t it? He is the living context and the constant question: For or against? He has had significant achievements—unemployment down, economy up, the courts, an imperfect tax bill that nonetheless got passed and was slightly better than what it replaced. No one seems to mention it, but America right now is enjoying prosperity and peace—or, if you prefer, growth and no new wars. It is a continuing amazement that with this the president can’t get himself to 50% approval, or his party in a better position.

Yet of course it’s no mystery. He obscures his victories with his crazy. And so in the weeks before the election he rants around about “Horseface,” and compares MBS to Justice Kavanaugh, the victim of unproved allegations. He continues to rag on Attorney General Jeff Sessions: “I could fire him whenever I want to fire him, but I haven’t said that I was going to.”

It is political malpractice on an epic scale and cannot be helped because he lacks self-command and is vain. He thinks nobody communicates like him. Nobody does. He thinks nobody breaks through like him. Nobody does!

In the first 18 months of his administration, those who pointed out that he’d made a good decision, or failed to castigate him enough, were sometimes accused of “normalizing” Mr. Trump. But normalizing him wasn’t within their power. Only Mr. Trump could normalize Mr. Trump, by enacting normality and self-possession. He could have opted for a certain stature—the presidential stage, with its flags and salutes, almost leads you by the hand to stature. But he hasn’t.

His supporters, especially Republican candidates, would love it if he’d put his arguments in the foreground, not his drama and weirdness. It is remarkable that he hasn’t cared about them enough to do this, to give them that kind of cover. He’s lucky the mainstream media hate him so much, and in showing that hatred stiffen his supporters’ loyalty.